Inflatable sports balls, such as for soccer and volleyball, are formed of multiple panels stitched together at seams formed along adjacent panel edges to form a cover, within which an inflatable bladder is placed prior to closure. The panels of these sports balls are typically stitched together by hand, although a pending application by the present inventor, as well as U.S. Pat. No. 5,759,123 and U.S. Pat. No. 5,772,545, describe air-inflatable sports balls with at least some of the panels joined by machine stitching.
The traditional hand stitch process is often facilitated by a device that consists of a triangular frame, formed, e.g., of bamboo or other suitable material, and open at the apex. A pair of panels to be stitched together is placed in the opening with the edges to be stitched and the stitch holes in alignment (typically the stitch holes are formed through both panels in a single punching or piercing operation). The worker then uses his or her legs to apply inwardly directed pressure to the opposite sides of the frame to grip the panels while he or she uses two hands to pass opposite ends of a stitching fiber or yarn through the holes, and to tighten the stitching fiber by pulling the ends in opposite directions. When stitching of an edge is completed, leg pressure against the frame is released, the stitched pair of panels is removed, and another pair of panels is placed within the frame opening for hand stitching.
The intensive hand labor required to hand stitch an inflatable sports ball dictates that manufacturing operations using traditional methods be conducted in countries with relatively low labor costs, i.e., countries of the Far East and Asia, such as China and Pakistan. The labor intensity of hand stitching also generally limits production to about four balls per working day for an average worker.